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A080930
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Sequence associated with recurrence a(n)=2*a(n-1)+k(k+2)*a(n-2).
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5
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1, 5, 20, 70, 224, 672, 1920, 5280, 14080, 36608, 93184, 232960, 573440, 1392640, 3342336, 7938048, 18677760, 43581440, 100925440, 232128512, 530579456, 1205862400, 2726297600, 6134169600, 13740539904, 30651973632, 68115496960
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| The fourth column of triangle A080928 is 4*A080930.
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FORMULA
| G.f.: (1-x)(1-2x+2x^2)/(1-2x)^4 = (1-3x+4x^2-2x^3)/(1-2x)^4
a(n)=binomial(n+3,3)*2^(n-3), n>=1 - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 29 2006
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MAPLE
| [seq (binomial(n+3, 3)*2^(n-3), n=1..27)]; - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 29 2006
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CROSSREFS
| Sequence in context: A055403 A160549 A089094 * A169792 A000343 A005324
Adjacent sequences: A080927 A080928 A080929 * A080931 A080932 A080933
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Feb 26 2003
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